1. Field of the Invention
The present invention relates to a tuneable electro-optic modulator and also to a method of tuning such a modulator. More particularly, but not exclusively, the present invention relates to a tuneable electro-optic modulator comprising first and second optically coupled electro-optic waveguides and a central optical waveguide having a tuning electrode therebetween.
2. Description of the Related Art
Mach Zehnder electro-optic modulators are known. The extinction ration of such modulators depends critically upon the optical coupling between the output waveguides. Small variations in coupling can produce large variations in extinction ratios. With modem optical waveguide fabrication technology it is difficult to control the ratio at which light couples between the waveguides with precision. Accordingly, the yield of such devices is low.